[PATCH bpf-next v3 1/2] bpf: use canonical ftrace path

[PATCH bpf-next v3 1/2] bpf: use canonical ftrace path

[zwisler]

From: Ross Zwisler <zwisler@google.com>

The canonical location for the tracefs filesystem is at /sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many comments and samples in the bpf code still refer to this older
debugfs path, so let's update them to avoid confusion.  There are a few
spots where the bpf code explicitly checks both tracefs and debugfs
(tools/bpf/bpftool/tracelog.c and tools/lib/api/fs/fs.c) and I've left
those alone so that the tools can continue to work with both paths.

Signed-off-by: Ross Zwisler <zwisler@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---

v2 was submitted to bpf-next via a pair of pull requests:
	https://github.com/kernel-patches/bpf/pull/4672
	https://github.com/kernel-patches/bpf/pull/4648

The only change since v2 is that I rebased on the current bpf-next_base.

I've run this through all the BPF selftests on a local machine:
	sudo ./test_verifier
	sudo make run_tests

and didn't hit any regressions.  I've also tested to make sure each
modified selftest runs successfully with each path of tracefs (with and
without debugfs).

---
 include/uapi/linux/bpf.h           | 8 ++++----
 samples/bpf/cpustat_kern.c         | 4 ++--
 samples/bpf/hbm.c                  | 4 ++--
 samples/bpf/ibumad_kern.c          | 4 ++--
 samples/bpf/lwt_len_hist.sh        | 2 +-
 samples/bpf/offwaketime_kern.c     | 2 +-
 samples/bpf/task_fd_query_user.c   | 4 ++--
 samples/bpf/test_lwt_bpf.sh        | 2 +-
 samples/bpf/test_overhead_tp.bpf.c | 4 ++--
 tools/include/uapi/linux/bpf.h     | 8 ++++----
 10 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d8c534e05b0a..13129df937cd 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1647,17 +1647,17 @@ union bpf_attr {
  * 	Description
  * 		This helper is a "printk()-like" facility for debugging. It
  * 		prints a message defined by format *fmt* (of size *fmt_size*)
- * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
  * 		available. It can take up to three additional **u64**
  * 		arguments (as an eBPF helpers, the total number of arguments is
  * 		limited to five).
  *
  * 		Each time the helper is called, it appends a line to the trace.
- * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
- * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
+ * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
  * 		The format of the trace is customizable, and the exact output
  * 		one will get depends on the options set in
- * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 		*\/sys/kernel/tracing/trace_options* (see also the
  * 		*README* file under the same directory). However, it usually
  * 		defaults to something like:
  *
diff --git a/samples/bpf/cpustat_kern.c b/samples/bpf/cpustat_kern.c
index 5aefd19cdfa1..944f13fe164a 100644
--- a/samples/bpf/cpustat_kern.c
+++ b/samples/bpf/cpustat_kern.c
@@ -76,8 +76,8 @@ struct {
 
 /*
  * The trace events for cpu_idle and cpu_frequency are taken from:
- * /sys/kernel/debug/tracing/events/power/cpu_idle/format
- * /sys/kernel/debug/tracing/events/power/cpu_frequency/format
+ * /sys/kernel/tracing/events/power/cpu_idle/format
+ * /sys/kernel/tracing/events/power/cpu_frequency/format
  *
  * These two events have same format, so define one common structure.
  */
diff --git a/samples/bpf/hbm.c b/samples/bpf/hbm.c
index 516fbac28b71..ff58ec43f56a 100644
--- a/samples/bpf/hbm.c
+++ b/samples/bpf/hbm.c
@@ -65,7 +65,7 @@ static void Usage(void);
 static void read_trace_pipe2(void);
 static void do_error(char *msg, bool errno_flag);
 
-#define DEBUGFS "/sys/kernel/debug/tracing/"
+#define TRACEFS "/sys/kernel/tracing/"
 
 static struct bpf_program *bpf_prog;
 static struct bpf_object *obj;
@@ -77,7 +77,7 @@ static void read_trace_pipe2(void)
 	FILE *outf;
 	char *outFname = "hbm_out.log";
 
-	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	trace_fd = open(TRACEFS "trace_pipe", O_RDONLY, 0);
 	if (trace_fd < 0) {
 		printf("Error opening trace_pipe\n");
 		return;
diff --git a/samples/bpf/ibumad_kern.c b/samples/bpf/ibumad_kern.c
index 9b193231024a..f07474c72525 100644
--- a/samples/bpf/ibumad_kern.c
+++ b/samples/bpf/ibumad_kern.c
@@ -39,8 +39,8 @@ struct {
 /* Taken from the current format defined in
  * include/trace/events/ib_umad.h
  * and
- * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_read/format
- * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_write/format
+ * /sys/kernel/tracing/events/ib_umad/ib_umad_read/format
+ * /sys/kernel/tracing/events/ib_umad/ib_umad_write/format
  */
 struct ib_umad_rw_args {
 	u64 pad;
diff --git a/samples/bpf/lwt_len_hist.sh b/samples/bpf/lwt_len_hist.sh
index 7078bfcc4f4d..381b2c634784 100755
--- a/samples/bpf/lwt_len_hist.sh
+++ b/samples/bpf/lwt_len_hist.sh
@@ -5,7 +5,7 @@ NS1=lwt_ns1
 VETH0=tst_lwt1a
 VETH1=tst_lwt1b
 BPF_PROG=lwt_len_hist.bpf.o
-TRACE_ROOT=/sys/kernel/debug/tracing
+TRACE_ROOT=/sys/kernel/tracing
 
 function cleanup {
 	# To reset saved histogram, remove pinned map
diff --git a/samples/bpf/offwaketime_kern.c b/samples/bpf/offwaketime_kern.c
index eb4d94742e6b..23f12b47e9e5 100644
--- a/samples/bpf/offwaketime_kern.c
+++ b/samples/bpf/offwaketime_kern.c
@@ -110,7 +110,7 @@ static inline int update_counts(void *ctx, u32 pid, u64 delta)
 }
 
 #if 1
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];
diff --git a/samples/bpf/task_fd_query_user.c b/samples/bpf/task_fd_query_user.c
index a33d74bd3a4b..1e61f2180470 100644
--- a/samples/bpf/task_fd_query_user.c
+++ b/samples/bpf/task_fd_query_user.c
@@ -235,7 +235,7 @@ static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
 	struct bpf_link *link;
 	ssize_t bytes;
 
-	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
+	snprintf(buf, sizeof(buf), "/sys/kernel/tracing/%s_events",
 		 event_type);
 	kfd = open(buf, O_WRONLY | O_TRUNC, 0);
 	CHECK_PERROR_RET(kfd < 0);
@@ -252,7 +252,7 @@ static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
 	close(kfd);
 	kfd = -1;
 
-	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
+	snprintf(buf, sizeof(buf), "/sys/kernel/tracing/events/%ss/%s/id",
 		 event_type, event_alias);
 	efd = open(buf, O_RDONLY, 0);
 	CHECK_PERROR_RET(efd < 0);
diff --git a/samples/bpf/test_lwt_bpf.sh b/samples/bpf/test_lwt_bpf.sh
index 2e9f5126963b..0bf2d0f6bf4b 100755
--- a/samples/bpf/test_lwt_bpf.sh
+++ b/samples/bpf/test_lwt_bpf.sh
@@ -21,7 +21,7 @@ IP_LOCAL="192.168.99.1"
 
 PROG_SRC="test_lwt_bpf.c"
 BPF_PROG="test_lwt_bpf.o"
-TRACE_ROOT=/sys/kernel/debug/tracing
+TRACE_ROOT=/sys/kernel/tracing
 CONTEXT_INFO=$(cat ${TRACE_ROOT}/trace_options | grep context)
 
 function lookup_mac()
diff --git a/samples/bpf/test_overhead_tp.bpf.c b/samples/bpf/test_overhead_tp.bpf.c
index 67cab3881969..8b498328e961 100644
--- a/samples/bpf/test_overhead_tp.bpf.c
+++ b/samples/bpf/test_overhead_tp.bpf.c
@@ -7,7 +7,7 @@
 #include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 
-/* from /sys/kernel/debug/tracing/events/task/task_rename/format */
+/* from /sys/kernel/tracing/events/task/task_rename/format */
 struct task_rename {
 	__u64 pad;
 	__u32 pid;
@@ -21,7 +21,7 @@ int prog(struct task_rename *ctx)
 	return 0;
 }
 
-/* from /sys/kernel/debug/tracing/events/fib/fib_table_lookup/format */
+/* from /sys/kernel/tracing/events/fib/fib_table_lookup/format */
 struct fib_table_lookup {
 	__u64 pad;
 	__u32 tb_id;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d8c534e05b0a..13129df937cd 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1647,17 +1647,17 @@ union bpf_attr {
  * 	Description
  * 		This helper is a "printk()-like" facility for debugging. It
  * 		prints a message defined by format *fmt* (of size *fmt_size*)
- * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
  * 		available. It can take up to three additional **u64**
  * 		arguments (as an eBPF helpers, the total number of arguments is
  * 		limited to five).
  *
  * 		Each time the helper is called, it appends a line to the trace.
- * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
- * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
+ * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
  * 		The format of the trace is customizable, and the exact output
  * 		one will get depends on the options set in
- * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 		*\/sys/kernel/tracing/trace_options* (see also the
  * 		*README* file under the same directory). However, it usually
  * 		defaults to something like:
  *

base-commit: d1d51a62d060d02f99ee407959e24ad10a40e053
prerequisite-patch-id: 9d1a70f239e7476600fe4018125df58a368dc725
prerequisite-patch-id: 29fea9a24684ec09762b277403d7bffffb25cdf3
prerequisite-patch-id: 9cb5a22a0f88413c393ddc29f264fbd96938c598
prerequisite-patch-id: 87ce0f3257a51e8cc06dd21ae3fa4102406ba4b4
prerequisite-patch-id: a46e67372e8493e5f7dab95f72281bd690cbeacf
prerequisite-patch-id: bae92ed6da92da5587f8d54fed5976c7dd6a468a
prerequisite-patch-id: c84726372fab0771a2c2ff0942f13a9556db8740
prerequisite-patch-id: 8a1a8806ec58ca208ee81f83557af90472fcba7f
prerequisite-patch-id: 0f7d6ec99549b042bc37603a2a9034853015a6d6
prerequisite-patch-id: 88a110f7993c374c6df429a1f67706e5abd65a02
prerequisite-patch-id: 3ada332d91275a471e9b65eb532571ef5caad4af
prerequisite-patch-id: e7ade2dda63127886579bf88f3eddda82d6a103b
prerequisite-patch-id: a49488cb1b167a9c85405c142cc3edb7bdb32c3d
prerequisite-patch-id: 9656ecd9c036e140d819c3929f01ac7264452382
prerequisite-patch-id: d1fa19bc1974a78632f48080b4eef3d4d6c07d3d
prerequisite-patch-id: 245b71b3aecf33a9d2a9609fc45f72ac50d1e92a
prerequisite-patch-id: 1253300de46fe258927fd3ddd5009a1468f6e69b
prerequisite-patch-id: 638e5805bdaa8842589729a26707c47a593464c2
prerequisite-patch-id: 1d08f9dfe4c360d566edbee925424b789e0f844b
prerequisite-patch-id: b6c73e77b10fc771566de294973334646cad4d44
prerequisite-patch-id: 57034da9a1b439c9fa3ecca69a099204a339502a
prerequisite-patch-id: ef11bfbcdf2239002958554e2dc5fbe8ec4d6e9a
prerequisite-patch-id: 68c01f7ca5b9c740b9259b73d97f168765c794d0
prerequisite-patch-id: 846110172a75fdaf1017da1fec3709fa301a5a47
prerequisite-patch-id: 8070c339fe5ce2e46b5de76b59d0a3f2c25d9abb
prerequisite-patch-id: c48cc68777605390db454b6392569ccdcd88cdc1
prerequisite-patch-id: 0d36d64d21de2d0df3ac31c5203a5cd868b4be47
prerequisite-patch-id: 6538cefc509c89e2375dcb6dc85d11fb6993474d
prerequisite-patch-id: dc57bbf1190a31aec332cab39f990ac568e6722d
prerequisite-patch-id: 0d90b60b4ce60024f31f576bab79453f6d480a8e
prerequisite-patch-id: 15c1914741be406aeee6c66332f079f3f8367751
prerequisite-patch-id: 78a735554858860fa695dd9e20bf7c5a41fafe20
prerequisite-patch-id: 238aaa7c1f55fdac815a6e14310d074c1ac70983
prerequisite-patch-id: d514061d937de74e8cc3d8848488a60dad2e2a2e
prerequisite-patch-id: 0f1a878f5768b886db78ea0fc6fe17d2297daa2e
prerequisite-patch-id: fa48be79a1e1e1c611d7975501a8f9dfa6f1c4fe
prerequisite-patch-id: 0a193e915faed8479f150c30ba0c335e288f634f
prerequisite-patch-id: 2cab00be3bb34454f98dac426301468e7ef12ad1
prerequisite-patch-id: daa2a81b90fda8ca09d11a35aff5a282e6f76ec2
prerequisite-patch-id: 5001694a51d83ed8ca428855b92b3ead261a469d
-- 
2.40.0.rc1.284.g88254d51c5-goog

[PATCH bpf-next v3 2/2] selftests/bpf: use canonical ftrace path

[zwisler]

From: Ross Zwisler <zwisler@google.com>

The canonical location for the tracefs filesystem is at /sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many tests in the bpf selftest code still refer to this older debugfs
path, so let's update them to avoid confusion.

Signed-off-by: Ross Zwisler <zwisler@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---
 tools/testing/selftests/bpf/get_cgroup_id_user.c    |  8 ++++++--
 .../selftests/bpf/prog_tests/kprobe_multi_test.c    |  7 ++++++-
 .../selftests/bpf/prog_tests/task_fd_query_tp.c     |  8 ++++++--
 .../selftests/bpf/prog_tests/tp_attach_query.c      |  8 ++++++--
 .../testing/selftests/bpf/prog_tests/trace_printk.c | 10 +++++++---
 .../selftests/bpf/prog_tests/trace_vprintk.c        | 10 +++++++---
 .../selftests/bpf/progs/test_stacktrace_map.c       |  2 +-
 tools/testing/selftests/bpf/progs/test_tracepoint.c |  2 +-
 tools/testing/selftests/bpf/test_ftrace.sh          |  7 ++++++-
 tools/testing/selftests/bpf/test_tunnel.sh          | 13 +++++++++----
 tools/testing/selftests/bpf/trace_helpers.c         |  8 ++++++--
 11 files changed, 61 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c
index 156743cf5870..4fa61ac8a0ee 100644
--- a/tools/testing/selftests/bpf/get_cgroup_id_user.c
+++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
@@ -86,8 +86,12 @@ int main(int argc, char **argv)
 	pid = getpid();
 	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
 
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/tracing/events/%s/id", probe_name);
+	else
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		goto close_prog;
diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index 113dba349a57..22be0a9a5a0a 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -338,7 +338,12 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
 	 * Filtering out duplicates by using hashmap__add, which won't
 	 * add existing entry.
 	 */
-	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
+	else
+		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+
 	if (!f)
 		return -EINVAL;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
index c717741bf8b6..60f92fd3c37a 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
@@ -17,8 +17,12 @@ static void test_task_fd_query_tp_core(const char *probe_name,
 	if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))
 		goto close_prog;
 
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/tracing/events/%s/id", probe_name);
+	else
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		goto close_prog;
diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
index 770fcc3bb1ba..d3e377fa8e9b 100644
--- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
+++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
@@ -16,8 +16,12 @@ void serial_test_tp_attach_query(void)
 	for (i = 0; i < num_progs; i++)
 		obj[i] = NULL;
 
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
+	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/tracing/events/sched/sched_switch/id");
+	else
+		snprintf(buf, sizeof(buf),
+			 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		return;
diff --git a/tools/testing/selftests/bpf/prog_tests/trace_printk.c b/tools/testing/selftests/bpf/prog_tests/trace_printk.c
index cade7f12315f..7b9124d506a5 100644
--- a/tools/testing/selftests/bpf/prog_tests/trace_printk.c
+++ b/tools/testing/selftests/bpf/prog_tests/trace_printk.c
@@ -5,7 +5,8 @@
 
 #include "trace_printk.lskel.h"
 
-#define TRACEBUF	"/sys/kernel/debug/tracing/trace_pipe"
+#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 #define SEARCHMSG	"testing,testing"
 
 void serial_test_trace_printk(void)
@@ -34,8 +35,11 @@ void serial_test_trace_printk(void)
 	if (!ASSERT_OK(err, "trace_printk__attach"))
 		goto cleanup;
 
-	fp = fopen(TRACEBUF, "r");
-	if (!ASSERT_OK_PTR(fp, "fopen(TRACEBUF)"))
+	if (access(TRACEFS_PIPE, F_OK) == 0)
+		fp = fopen(TRACEFS_PIPE, "r");
+	else
+		fp = fopen(DEBUGFS_PIPE, "r");
+	if (!ASSERT_OK_PTR(fp, "fopen(TRACE_PIPE)"))
 		goto cleanup;
 
 	/* We do not want to wait forever if this test fails... */
diff --git a/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c b/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
index 7a4e313e8558..44ea2fd88f4c 100644
--- a/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
+++ b/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
@@ -5,7 +5,8 @@
 
 #include "trace_vprintk.lskel.h"
 
-#define TRACEBUF	"/sys/kernel/debug/tracing/trace_pipe"
+#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 #define SEARCHMSG	"1,2,3,4,5,6,7,8,9,10"
 
 void serial_test_trace_vprintk(void)
@@ -27,8 +28,11 @@ void serial_test_trace_vprintk(void)
 	if (!ASSERT_OK(err, "trace_vprintk__attach"))
 		goto cleanup;
 
-	fp = fopen(TRACEBUF, "r");
-	if (!ASSERT_OK_PTR(fp, "fopen(TRACEBUF)"))
+	if (access(TRACEFS_PIPE, F_OK) == 0)
+		fp = fopen(TRACEFS_PIPE, "r");
+	else
+		fp = fopen(DEBUGFS_PIPE, "r");
+	if (!ASSERT_OK_PTR(fp, "fopen(TRACE_PIPE)"))
 		goto cleanup;
 
 	/* We do not want to wait forever if this test fails... */
diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
index 728dbd39eff0..47568007b668 100644
--- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
+++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
@@ -38,7 +38,7 @@ struct {
 	__type(value, stack_trace_t);
 } stack_amap SEC(".maps");
 
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];
diff --git a/tools/testing/selftests/bpf/progs/test_tracepoint.c b/tools/testing/selftests/bpf/progs/test_tracepoint.c
index 43bd7a20cc50..4cb8bbb6a320 100644
--- a/tools/testing/selftests/bpf/progs/test_tracepoint.c
+++ b/tools/testing/selftests/bpf/progs/test_tracepoint.c
@@ -4,7 +4,7 @@
 #include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];
diff --git a/tools/testing/selftests/bpf/test_ftrace.sh b/tools/testing/selftests/bpf/test_ftrace.sh
index 20de7bb873bc..f5109eb0e951 100755
--- a/tools/testing/selftests/bpf/test_ftrace.sh
+++ b/tools/testing/selftests/bpf/test_ftrace.sh
@@ -1,6 +1,11 @@
 #!/bin/bash
 
-TR=/sys/kernel/debug/tracing/
+if [[ -e /sys/kernel/tracing/trace ]]; then
+    TR=/sys/kernel/tracing/
+else
+    TR=/sys/kernel/debug/tracing/
+fi
+
 clear_trace() { # reset trace output
     echo > $TR/trace
 }
diff --git a/tools/testing/selftests/bpf/test_tunnel.sh b/tools/testing/selftests/bpf/test_tunnel.sh
index 06857b689c11..2dec7dbf29a2 100755
--- a/tools/testing/selftests/bpf/test_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tunnel.sh
@@ -571,8 +571,13 @@ setup_xfrm_tunnel()
 
 test_xfrm_tunnel()
 {
+	if [[ -e /sys/kernel/tracing/trace ]]; then
+		TRACE=/sys/kernel/tracing/trace
+	else
+		TRACE=/sys/kernel/debug/tracing/trace
+	fi
 	config_device
-	> /sys/kernel/debug/tracing/trace
+	> ${TRACE}
 	setup_xfrm_tunnel
 	mkdir -p ${BPF_PIN_TUNNEL_DIR}
 	bpftool prog loadall ${BPF_FILE} ${BPF_PIN_TUNNEL_DIR}
@@ -581,11 +586,11 @@ test_xfrm_tunnel()
 		${BPF_PIN_TUNNEL_DIR}/xfrm_get_state
 	ip netns exec at_ns0 ping $PING_ARG 10.1.1.200
 	sleep 1
-	grep "reqid 1" /sys/kernel/debug/tracing/trace
+	grep "reqid 1" ${TRACE}
 	check_err $?
-	grep "spi 0x1" /sys/kernel/debug/tracing/trace
+	grep "spi 0x1" ${TRACE}
 	check_err $?
-	grep "remote ip 0xac100164" /sys/kernel/debug/tracing/trace
+	grep "remote ip 0xac100164" ${TRACE}
 	check_err $?
 	cleanup
 
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 09a16a77bae4..934bf28fc888 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -12,7 +12,8 @@
 #include <sys/mman.h>
 #include "trace_helpers.h"
 
-#define DEBUGFS "/sys/kernel/debug/tracing/"
+#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 
 #define MAX_SYMS 300000
 static struct ksym syms[MAX_SYMS];
@@ -136,7 +137,10 @@ void read_trace_pipe(void)
 {
 	int trace_fd;
 
-	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	if (access(TRACEFS_PIPE, F_OK) == 0)
+		trace_fd = open(TRACEFS_PIPE, O_RDONLY, 0);
+	else
+		trace_fd = open(DEBUGFS_PIPE, O_RDONLY, 0);
 	if (trace_fd < 0)
 		return;
 
-- 
2.40.0.rc1.284.g88254d51c5-goog

Re: [PATCH bpf-next v3 2/2] selftests/bpf: use canonical ftrace path

[Steven Rostedt]

On Fri, 10 Mar 2023 10:52:09 -0700
zwisler@kernel.org wrote:

> diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> index 156743cf5870..4fa61ac8a0ee 100644
> --- a/tools/testing/selftests/bpf/get_cgroup_id_user.c
> +++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> @@ -86,8 +86,12 @@ int main(int argc, char **argv)
>  	pid = getpid();
>  	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
>  
> -	snprintf(buf, sizeof(buf),
> -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> +		snprintf(buf, sizeof(buf),
> +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> +	else
> +		snprintf(buf, sizeof(buf),
> +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);

I don't know how the BPF folks feel, but I do know some kernel developers
prefer that if you need to break a single command into multiple lines that
you then need to add brackets around it. As it makes it easier to read.

	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
		snprintf(buf, sizeof(buf),
			 "/sys/kernel/tracing/events/%s/id", probe_name);
	} else {
		snprintf(buf, sizeof(buf),
			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
	}



>  	efd = open(buf, O_RDONLY, 0);
>  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
>  		goto close_prog;
> diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> index 113dba349a57..22be0a9a5a0a 100644
> --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> @@ -338,7 +338,12 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
>  	 * Filtering out duplicates by using hashmap__add, which won't
>  	 * add existing entry.
>  	 */
> -	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> +
> +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> +		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
> +	else
> +		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> +
>  	if (!f)
>  		return -EINVAL;
>  
> diff --git a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> index c717741bf8b6..60f92fd3c37a 100644
> --- a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> +++ b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> @@ -17,8 +17,12 @@ static void test_task_fd_query_tp_core(const char *probe_name,
>  	if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))
>  		goto close_prog;
>  
> -	snprintf(buf, sizeof(buf),
> -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> +		snprintf(buf, sizeof(buf),
> +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> +	else
> +		snprintf(buf, sizeof(buf),
> +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);

Same here.

>  	efd = open(buf, O_RDONLY, 0);
>  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
>  		goto close_prog;
> diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> index 770fcc3bb1ba..d3e377fa8e9b 100644
> --- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> +++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> @@ -16,8 +16,12 @@ void serial_test_tp_attach_query(void)
>  	for (i = 0; i < num_progs; i++)
>  		obj[i] = NULL;
>  
> -	snprintf(buf, sizeof(buf),
> -		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> +		snprintf(buf, sizeof(buf),
> +			 "/sys/kernel/tracing/events/sched/sched_switch/id");
> +	else
> +		snprintf(buf, sizeof(buf),
> +			 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");

and here.

But perhaps the BPF folks don't care?

-- Steve

>  	efd = open(buf, O_RDONLY, 0);
>  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
>  		return;

Re: [PATCH bpf-next v3 1/2] bpf: use canonical ftrace path

[Steven Rostedt]

On Fri, 10 Mar 2023 10:52:08 -0700
zwisler@kernel.org wrote:

> From: Ross Zwisler <zwisler@google.com>
> 
> The canonical location for the tracefs filesystem is at /sys/kernel/tracing.
> 
> But, from Documentation/trace/ftrace.rst:
> 
>   Before 4.1, all ftrace tracing control files were within the debugfs
>   file system, which is typically located at /sys/kernel/debug/tracing.
>   For backward compatibility, when mounting the debugfs file system,
>   the tracefs file system will be automatically mounted at:
> 
>   /sys/kernel/debug/tracing
> 
> Many comments and samples in the bpf code still refer to this older
> debugfs path, so let's update them to avoid confusion.  There are a few
> spots where the bpf code explicitly checks both tracefs and debugfs
> (tools/bpf/bpftool/tracelog.c and tools/lib/api/fs/fs.c) and I've left
> those alone so that the tools can continue to work with both paths.
> 
> Signed-off-by: Ross Zwisler <zwisler@google.com>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>

Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve

Re: [PATCH bpf-next v3 2/2] selftests/bpf: use canonical ftrace path

[Ross Zwisler]

On Fri, Mar 10, 2023 at 06:33:52PM -0500, Steven Rostedt wrote:
> On Fri, 10 Mar 2023 10:52:09 -0700
> zwisler@kernel.org wrote:
> 
> > diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > index 156743cf5870..4fa61ac8a0ee 100644
> > --- a/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > +++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > @@ -86,8 +86,12 @@ int main(int argc, char **argv)
> >  	pid = getpid();
> >  	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> >  
> > -	snprintf(buf, sizeof(buf),
> > -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > +		snprintf(buf, sizeof(buf),
> > +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > +	else
> > +		snprintf(buf, sizeof(buf),
> > +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> 
> I don't know how the BPF folks feel, but I do know some kernel developers
> prefer that if you need to break a single command into multiple lines that
> you then need to add brackets around it. As it makes it easier to read.
> 
> 	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
> 		snprintf(buf, sizeof(buf),
> 			 "/sys/kernel/tracing/events/%s/id", probe_name);
> 	} else {
> 		snprintf(buf, sizeof(buf),
> 			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> 	}
> 
> 
> 
> >  	efd = open(buf, O_RDONLY, 0);
> >  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> >  		goto close_prog;
> > diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > index 113dba349a57..22be0a9a5a0a 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > @@ -338,7 +338,12 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
> >  	 * Filtering out duplicates by using hashmap__add, which won't
> >  	 * add existing entry.
> >  	 */
> > -	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> > +
> > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > +		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
> > +	else
> > +		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> > +
> >  	if (!f)
> >  		return -EINVAL;
> >  
> > diff --git a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > index c717741bf8b6..60f92fd3c37a 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > @@ -17,8 +17,12 @@ static void test_task_fd_query_tp_core(const char *probe_name,
> >  	if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))
> >  		goto close_prog;
> >  
> > -	snprintf(buf, sizeof(buf),
> > -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > +		snprintf(buf, sizeof(buf),
> > +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > +	else
> > +		snprintf(buf, sizeof(buf),
> > +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> 
> Same here.
> 
> >  	efd = open(buf, O_RDONLY, 0);
> >  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> >  		goto close_prog;
> > diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > index 770fcc3bb1ba..d3e377fa8e9b 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > @@ -16,8 +16,12 @@ void serial_test_tp_attach_query(void)
> >  	for (i = 0; i < num_progs; i++)
> >  		obj[i] = NULL;
> >  
> > -	snprintf(buf, sizeof(buf),
> > -		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > +		snprintf(buf, sizeof(buf),
> > +			 "/sys/kernel/tracing/events/sched/sched_switch/id");
> > +	else
> > +		snprintf(buf, sizeof(buf),
> > +			 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> 
> and here.
> 
> But perhaps the BPF folks don't care?

Sure, I agree that this is more readable.  I'll gather your Reviewed-by for
patch #1, make this change, rebase to the current bpf/bpf-next and send out
v4.

Re: [PATCH bpf-next v3 2/2] selftests/bpf: use canonical ftrace path

[John Fastabend]

Ross Zwisler wrote:
> On Fri, Mar 10, 2023 at 06:33:52PM -0500, Steven Rostedt wrote:
> > On Fri, 10 Mar 2023 10:52:09 -0700
> > zwisler@kernel.org wrote:
> > 
> > > diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > > index 156743cf5870..4fa61ac8a0ee 100644
> > > --- a/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > > +++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > > @@ -86,8 +86,12 @@ int main(int argc, char **argv)
> > >  	pid = getpid();
> > >  	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> > >  
> > > -	snprintf(buf, sizeof(buf),
> > > -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > > +	else
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > 
> > I don't know how the BPF folks feel, but I do know some kernel developers
> > prefer that if you need to break a single command into multiple lines that
> > you then need to add brackets around it. As it makes it easier to read.
> > 
> > 	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
> > 		snprintf(buf, sizeof(buf),
> > 			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > 	} else {
> > 		snprintf(buf, sizeof(buf),
> > 			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > 	}
> > 
> > 
> > 
> > >  	efd = open(buf, O_RDONLY, 0);
> > >  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> > >  		goto close_prog;
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > > index 113dba349a57..22be0a9a5a0a 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > > @@ -338,7 +338,12 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
> > >  	 * Filtering out duplicates by using hashmap__add, which won't
> > >  	 * add existing entry.
> > >  	 */
> > > -	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> > > +
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
> > > +	else
> > > +		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> > > +
> > >  	if (!f)
> > >  		return -EINVAL;
> > >  
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > > index c717741bf8b6..60f92fd3c37a 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > > @@ -17,8 +17,12 @@ static void test_task_fd_query_tp_core(const char *probe_name,
> > >  	if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))
> > >  		goto close_prog;
> > >  
> > > -	snprintf(buf, sizeof(buf),
> > > -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > > +	else
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > 
> > Same here.
> > 
> > >  	efd = open(buf, O_RDONLY, 0);
> > >  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> > >  		goto close_prog;
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > > index 770fcc3bb1ba..d3e377fa8e9b 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > > @@ -16,8 +16,12 @@ void serial_test_tp_attach_query(void)
> > >  	for (i = 0; i < num_progs; i++)
> > >  		obj[i] = NULL;
> > >  
> > > -	snprintf(buf, sizeof(buf),
> > > -		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/tracing/events/sched/sched_switch/id");
> > > +	else
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> > 
> > and here.
> > 
> > But perhaps the BPF folks don't care?
> 
> Sure, I agree that this is more readable.  I'll gather your Reviewed-by for
> patch #1, make this change, rebase to the current bpf/bpf-next and send out
> v4.


Also for the patch. LGTM

Acked-by: John Fastabend <john.fastabend@gmail.com>